1. Field of the Invention
The present invention relates generally to an enzymatic mediated polymerization process of hydroxytyrosol in an aqueous solvent which results in a novel polymer of polyphenol. This polymerized phenol exhibits improved electrical and optical properties, water solubility, and processability compared to phenolic resins and traditional phenols. It is synthesized using chemically safe and environmentally friendly conditions for use in a variety of applications including as an antioxidant for foods.
2. Description of the Related Art
Phenolic polymers, in particular phenol-formaldehyde resins such as novolaks and resols find wide application as wood composites laminates, foundry resins, abrasives, friction and molding materials, coatings and adhesives, fiber bonders and flame retardants. There has been a major concern, however, over the toxic effects of formaldehyde which are used in current art synthetic processes. In recent years there has been a tremendous surge towards the development of an alternative synthetic route, which circumvents the toxic effects of formaldehyde. Enzymatic polymerization of phenol in aqueous solutions was initially investigated as a possible benign and environmentally friendly solution to the synthesis of polyphenols (Akkara J. et al.). (J. A. Akkara, K. J. Senecal, and D. L. Kaplan, Jour. of Pol. Sci.: Part A: Pol. Chem., 29, 1561, (1991)).
These initial attempts, however, were unsuccessful since only very low molecular weight oligomers could be formed which had limited useful properties to meet the requirements for such applications. Alternative enzymatic reactions have since been investigated to improve molecular weight and the mechanical, thermal, optical and electronic properties of these polymers; such as micelles, air-water interface monolayers and mixture into various organic solvents. Although the molecular weights and properties of these polyphenols were improved, their commercial application remained limited due to extensive branching and poor solubility and processability of the resulting polymers (Madhu Ayyagari, Kenneth A. Marx, Sukant K. Tripathy, Joseph A. Akkara, and David L. Kaplan: “Controlled Free-Radical Polymerization of Phenol Derivatives by Enzyme-Catalyzed Reactions in Organic Solvents” Macromolecules 1995, 28, 5192).